US5192715A - Process for avoiding spin-on-glass cracking in high aspect ratio cavities - Google Patents

Process for avoiding spin-on-glass cracking in high aspect ratio cavities Download PDF

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US5192715A
US5192715A US07/873,920 US87392092A US5192715A US 5192715 A US5192715 A US 5192715A US 87392092 A US87392092 A US 87392092A US 5192715 A US5192715 A US 5192715A
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spin
glass
interconnects
tungsten
interconnect
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US07/873,920
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John W. Sliwa, Jr.
Pankaj Dixit
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Advanced Micro Devices Inc
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Advanced Micro Devices Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
    • H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
    • H01L23/5222—Capacitive arrangements or effects of, or between wiring layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
    • H01L21/7682—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing the dielectric comprising air gaps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
    • H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
    • H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
    • H01L23/532—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body characterised by the materials
    • H01L23/5329—Insulating materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S438/00—Semiconductor device manufacturing: process
    • Y10S438/902—Capping layer

Definitions

  • the present invention relates generally to multilevel interconnections formed in integrated circuits (ICs) employing spin-on-glass planarization.
  • an object of the present invention to provide an SOG dielectric structure which eliminates stress-cracking of spin-on glass used in multi-level metal interconnects such that no CVD dielectrics are required for stress-cracking avoidance.
  • a structure and process are provided for relieving stress in spin-on-glass employed in multi-level interconnects.
  • a selective tungsten coating is grown on the exposed surfaces of the low-resistivity metal interconnects which are to be planarized with an overlying dielectric.
  • Spin-on-glass is then blanket-deposited everywhere, including between interconnects, typically with the usual spinner application method known to the art.
  • the spin-on-glass is then soft-cured and etched back to expose the surfaces of the metal interconnects.
  • the tungsten coating is removed from the tops and sides of the metal interconnects, which acts not only to relieve the initial small stress in the SOG due to soft curing but also mechanically decouples the SOG from the interconnects before it undergoes the shrinkage associated with the hard curing process.
  • the tungsten removal leaves laterally free-standing spin-on-glass, which is then hard-cured.
  • the tungsten removal effectively renders the aspect ratio as unimportant from a stress point of view. This is because the interconnects no longer hinder SOG shrinkage. In fact, now high aspect ratio "towers" of SOG will actually have lower stress than non-decoupled low-aspect ratio SOG regions.
  • a capping layer of spin-on-glass is deposited, soft-cured, and then hard-cured. In this manner, cracking of the spin-on-glass is avoided.
  • interconnect structures having aspect ratios of 1 and greater, thus obtaining higher speed through the use of thicker, lower resistance interconnects as well as more compact devices in cases where lateral fringe capacitance is not dominating. Given the process and structure, the cost and complexity of the planarization process is dramatically reduced.
  • FIGS. 1-3 are cross-sectional views of the process of the invention.
  • FIG. 4 is a cross-sectional view depicting an alternate embodiment.
  • the metal interconnects 10 may comprise aluminum or an alloy thereof or other low resistivity metal, as is well-known in the art.
  • the metal interconnects are separated by a space 14.
  • a space 14 there are, of course, a plurality of separated metal interconnects 10 formed on the surface of at least one dielectric level 12.
  • Each of these interconnect levels has to be patterned and then planarized and insulated with a dielectric material.
  • spin-on-glass (SOG) is used in connection with CVD oxides, since SOG is convenient to apply and is a low cost process compared to not using SOG and planarizing CVD oxides with resist-etchback methods instead.
  • a selective tungsten coating 16 typically about 500 to 3,000 ⁇ thick is grown on the metal interconnects 10 having a pitch and thickness such that the cavity (before tunqsten deposition) has an aspect ratio (height H/width W) ⁇ 1.
  • the selectivity of the selective tungsten process is rapidly degraded as thickness is increased into the 5,000 to 10,000 range.
  • selective tungsten is preferably deposited in the self-limiting thickness regime of about 500 to 900 ⁇ , for example, at about 700 ⁇ , where the selectivity is essentially perfect.
  • the tungsten coating 16 covers the exposed interconnects 10, typically the tops 10a and sides 10b, as shown in FIG. 1.
  • the conditions of the soft-cure process per se are well-known in the art and thus do not form a part of this invention.
  • successively higher temperatures are applied to the wafer using a set of sequential hot-plates on which the wafer is placed by a robotic arm. In this manner, the cure is gradual and occurs from the bottom upwards so that solvent can escape.
  • Multiple increasing temperatures also minimize stress and bubbles. Temperatures much higher than about 250° C. for the hottest step build in too much stress, whereas temperatures much lower than about 125° C.
  • conditions could be 150° ⁇ 25° C. for about 1 to 2 minutes, 200° ⁇ 25° C. for about 1 to 2 minutes, and 250° C. for about 1 to 2 minutes. Once the parameters are chosen, they are typically fixed to ⁇ 2° C. and ⁇ 2 seconds.
  • the thickness of the SOG coating is chosen to be sufficient to more than cover the interconnects. As is known, the thickness can be influenced either by spin speed or solvent/solids content manipulation.
  • the SOG is then etched back in the typical oxygen/-chlorofluoro chemistries to expose the tops 10a of the metal interconnects 10, as shown in FIG. 2.
  • the original SOG coating prior to the etchback is shown in phantom and denoted 18' in FIG. 2. If the tungsten 16 on the sidewalls 10b is not already gone at this point, it is then completely removed by a wet dip which contains H 2 O 2 or any other isotropic wet or dry etchant which does not attack aluminum or soft-cured SOG. Such a dip also serves to clean up organic residue from the etch-back process. This leaves laterally free-standing SOG portions 18 which can now be hardcured.
  • FIG. 2 shows the SOG portions 18 after the hard-cure, detached from the sidewalls 10b of the interconnects 10.
  • voids 20 are formed between the aluminum interconnects 10 and the SOG 18, due to the removal of the tungsten coating 16. These voids 20 are wider at the top, due to the SOG shrinkage during hard cure which would have otherwise caused immediate high tensile stress and subsequent tensile failure either immediately or upon later wafer processing or device packaging.
  • FIG. 3 shows the completed structure.
  • the metal sidewall voids 20 (seen in FIG. 2), actually slits, will not crack with the new SOG, due to the cumulative shrinkage strain being almost zero over such a small lateral gap. Even if it did crack, such a crack would be virtually invisible and structurally insignificant.
  • the material comprising the capping layer 22 may alternatively comprise plasma CVD TEOS (tetra-ethyl ortho silicate) oxide, deposited at ⁇ 410° C., as is well-known in the art.
  • Alternative dielectric capping layers 22 include polyimides, silicones, silicon oxides, silicon nitrides, or silicon oxynitrides. Such dielectric materials may be applied by such well-known processes as LPCVD (low pressure CVD), PECVD (plasma enhanced CVD), or PVD (physical vapor deposition). Such processes employ chemicals and temperatures that are compatible with the metal interconnects 10.
  • LPCVD low pressure CVD
  • PECVD plasma enhanced CVD
  • PVD physical vapor deposition
  • the capping layer 22' of FIG. 4 is chosen to be CVD or PVD oxide rather than SOG because it will leave voids 24 unfilled.
  • CMOS complementary metal oxide semiconductor
  • BiCMOS bipolar CMOS
  • NMOS complementary metal oxide semiconductor
  • examples include four-level metal bipolar ECL (emitter coupled logic) gate arrays, very high speed logic devices, SRAMs (static random access memories), DRAMs (dynamic random access memories) and high speed multi-metal EPROMs (erasable programmable read-only memories).

Abstract

Before spin-on-glass (SOG) is applied and soft-cured over metal traces (10) having a height/width aspect ratio (of the spaces) of at least 1, the aluminum metal traces are selectively coated with selective tungsten (16). After SOG (18) is spun on and soft-cured, it is etched back to expose the metal interconnects. A selective tungsten wet etch in H2 O2 detaches the SOG from the metal walls, leaving silt-like voids (20). Stress-free SOG hard curing may now proceed. A capping layer (22) of SOG may now be applied, soft-cured, then hard-cured. Alternatively, other dielectric materials may be applied as the capping layer. Further, interfacial lateral sidewall voids (24) may be deliberately left unfilled, by employing a capping layer (22') of vapor-deposited oxide. The unfilled voids have a dielectric constant of 1.0, which is useful in extremely high speed devices. The resulting structure is comparatively stress-free as fabricated and is resistant to later environmentally-induced brittle tensile fracture.

Description

This is a division of application Ser. No. 07/652,306, filed Feb. 5, 1991, U.S. Pat. No. 5,119,164 which in turn is a continuation of application Ser. No. 07/385,649, filed Jul. 25, 1989, abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to multilevel interconnections formed in integrated circuits (ICs) employing spin-on-glass planarization.
2. Description of the Related Art
Spin-on-glasses typically crack when hard-cured in cavities of aspect ratio greater than one due to tensile brittle fracture induced by shrinkage. This is especially true when the spin-on-glass (SOG) is subjected to later thermal shock and cycling. It is also especially true when the spin-on-glass is not fully encapsulated by other CVD-based oxides. This is unfortunate, since such encapsulation is cost-intensive and defect-prone. To avoid this problem, aspect ratios must be kept to ≦1 to provide acceptable process yields and process margins. Frequently, double spins of SOG and even interleaved chemical vapor depositions (CVD) between SOG spins are required to approach an SOG aspect ratio (height/width) of 1 or greater. This has the effect of minimizing the maximum shrinkage and thus the maximum stress and thus the cracking tendency. Such elaborate measures increase the process cost, and they still limit device packing density, which could benefit by aspect ratios of 2 to 3 which are beyond the reach of such measures.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an SOG dielectric structure which eliminates stress-cracking of spin-on glass used in multi-level metal interconnects such that no CVD dielectrics are required for stress-cracking avoidance.
It is another object of the present invention to provide a process for implementing such a structure using existing SOG materials in a manner such that the stresses are actively and purposefully relieved.
In accordance with the invention, a structure and process are provided for relieving stress in spin-on-glass employed in multi-level interconnects. In the process, a selective tungsten coating is grown on the exposed surfaces of the low-resistivity metal interconnects which are to be planarized with an overlying dielectric. Spin-on-glass is then blanket-deposited everywhere, including between interconnects, typically with the usual spinner application method known to the art. The spin-on-glass is then soft-cured and etched back to expose the surfaces of the metal interconnects. Next, the tungsten coating is removed from the tops and sides of the metal interconnects, which acts not only to relieve the initial small stress in the SOG due to soft curing but also mechanically decouples the SOG from the interconnects before it undergoes the shrinkage associated with the hard curing process. Thus, the tungsten removal leaves laterally free-standing spin-on-glass, which is then hard-cured. The tungsten removal effectively renders the aspect ratio as unimportant from a stress point of view. This is because the interconnects no longer hinder SOG shrinkage. In fact, now high aspect ratio "towers" of SOG will actually have lower stress than non-decoupled low-aspect ratio SOG regions. Finally, a capping layer of spin-on-glass is deposited, soft-cured, and then hard-cured. In this manner, cracking of the spin-on-glass is avoided.
Using the teachings of this invention, one may create interconnect structures having aspect ratios of 1 and greater, thus obtaining higher speed through the use of thicker, lower resistance interconnects as well as more compact devices in cases where lateral fringe capacitance is not dominating. Given the process and structure, the cost and complexity of the planarization process is dramatically reduced.
Other objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description and accompanying drawings, in which like reference designations represent like features throughout the FIGURES.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings referred to in this description should be understood as not being drawn to scale except if specifically noted. Moreover, the drawings are intended to illustrate only one portion of an integrated circuit fabricated in accordance with the present invention.
FIGS. 1-3 are cross-sectional views of the process of the invention; and
FIG. 4 is a cross-sectional view depicting an alternate embodiment.
DETAILED DESCRIPTION OF THE INVENTION
Reference is now made in detail to a specific embodiment of the present invention, which illustrates the best mode presently contemplated by the inventors for practicing the invention. Alternative embodiments are also briefly described as applicable.
Shown in FIG. 1 are two metal interconnects 10 formed on a dielectric substrate 12. The metal interconnects 10 may comprise aluminum or an alloy thereof or other low resistivity metal, as is well-known in the art.
The metal interconnects are separated by a space 14. In the practice of the invention, there are, of course, a plurality of separated metal interconnects 10 formed on the surface of at least one dielectric level 12. Each of these interconnect levels has to be patterned and then planarized and insulated with a dielectric material. At the present time, spin-on-glass (SOG) is used in connection with CVD oxides, since SOG is convenient to apply and is a low cost process compared to not using SOG and planarizing CVD oxides with resist-etchback methods instead.
In the process of the invention, a selective tungsten coating 16, typically about 500 to 3,000 Å thick is grown on the metal interconnects 10 having a pitch and thickness such that the cavity (before tunqsten deposition) has an aspect ratio (height H/width W) ≧1. As is known to the art, the selectivity of the selective tungsten process is rapidly degraded as thickness is increased into the 5,000 to 10,000 range. Accordingly, selective tungsten is preferably deposited in the self-limiting thickness regime of about 500 to 900 Å, for example, at about 700 Å, where the selectivity is essentially perfect. The tungsten coating 16 covers the exposed interconnects 10, typically the tops 10a and sides 10b, as shown in FIG. 1.
An SOG coating 18, such as an Allied 100 Series or 200 Series SOG, is spun on thick and soft-cured, typically for 1 minute at each of three increasing temperatures, of which the last and highest is ≈250° C. The conditions of the soft-cure process per se are well-known in the art and thus do not form a part of this invention. In general, successively higher temperatures are applied to the wafer using a set of sequential hot-plates on which the wafer is placed by a robotic arm. In this manner, the cure is gradual and occurs from the bottom upwards so that solvent can escape. Multiple increasing temperatures also minimize stress and bubbles. Temperatures much higher than about 250° C. for the hottest step build in too much stress, whereas temperatures much lower than about 125° C. will cause non-uniform dry-etching and poor resistance to tungsten wet-etchant to be used later in the process. In general, conditions could be 150° ±25° C. for about 1 to 2 minutes, 200° ±25° C. for about 1 to 2 minutes, and 250° C. for about 1 to 2 minutes. Once the parameters are chosen, they are typically fixed to ±2° C. and ±2 seconds.
The thickness of the SOG coating is chosen to be sufficient to more than cover the interconnects. As is known, the thickness can be influenced either by spin speed or solvent/solids content manipulation.
The SOG is then etched back in the typical oxygen/-chlorofluoro chemistries to expose the tops 10a of the metal interconnects 10, as shown in FIG. 2. The original SOG coating prior to the etchback is shown in phantom and denoted 18' in FIG. 2. If the tungsten 16 on the sidewalls 10b is not already gone at this point, it is then completely removed by a wet dip which contains H2 O2 or any other isotropic wet or dry etchant which does not attack aluminum or soft-cured SOG. Such a dip also serves to clean up organic residue from the etch-back process. This leaves laterally free-standing SOG portions 18 which can now be hardcured. The conditions of the hard-cure process per se are well-known in the prior art and thus do not form a part of this invention. Typically, it involves a 400° C. exposure for at least 30 minutes. The significant fact is that the hard cure, necessary to gain the final SOG properties, is normally what induces shrinkage cracking or incipient cracking and large tensile stress. The shrinkage must occur for the required molecular restructuring to take place. FIG. 2 shows the SOG portions 18 after the hard-cure, detached from the sidewalls 10b of the interconnects 10.
It will be noted that voids 20 are formed between the aluminum interconnects 10 and the SOG 18, due to the removal of the tungsten coating 16. These voids 20 are wider at the top, due to the SOG shrinkage during hard cure which would have otherwise caused immediate high tensile stress and subsequent tensile failure either immediately or upon later wafer processing or device packaging.
Next, a capping SOG layer 22 is spun on and soft-cured, then hard-cured directly. The conditions of the soft-cure and hard cure processes are within the known prior art values. FIG. 3 shows the completed structure. The metal sidewall voids 20 (seen in FIG. 2), actually slits, will not crack with the new SOG, due to the cumulative shrinkage strain being almost zero over such a small lateral gap. Even if it did crack, such a crack would be virtually invisible and structurally insignificant. The material comprising the capping layer 22 may alternatively comprise plasma CVD TEOS (tetra-ethyl ortho silicate) oxide, deposited at ≈410° C., as is well-known in the art.
Alternative dielectric capping layers 22 include polyimides, silicones, silicon oxides, silicon nitrides, or silicon oxynitrides. Such dielectric materials may be applied by such well-known processes as LPCVD (low pressure CVD), PECVD (plasma enhanced CVD), or PVD (physical vapor deposition). Such processes employ chemicals and temperatures that are compatible with the metal interconnects 10.
In this manner, SOG stresses are not permitted to build up and CVD layers can potentially be completely eliminated, since they are not needed to keep the SOG material to a minimum both in volume and aspect ratio. It should be noted that this tungsten deposition/SOG etch-back/tungsten strip/SOG hard-cure process could be done more than once at a given level of interconnect if the SOG is etched back beyond the surface of the metal. In this manner, aspect ratios of 2 or 3 and even greater are obtainable, yet at no time does any free-standing SOG element approach such a high aspect ratio, thus minimizing the additional concern of vibration-induced SOG fracture.
In an alternative embodiment, the selective tungsten 16 may be relatively thick, say about 1,000 to 3,000 Å, such that when it is stripped, one may cap with CVD oxide 22', leaving behind permanent interfacial lateral sidewall voids 24 (FIG. 4) of dielectric constant =1.0 for extremely high speed. The capping layer 22' of FIG. 4 is chosen to be CVD or PVD oxide rather than SOG because it will leave voids 24 unfilled.
The process of the invention may be used in any multi-level IC which can employ spin-on-glass planarization, such as CMOS (complementary metal oxide semiconductor), BiCMOS (bipolar CMOS), bipolar, or NMOS technologies, as well as for GaAs technologies. Examples include four-level metal bipolar ECL (emitter coupled logic) gate arrays, very high speed logic devices, SRAMs (static random access memories), DRAMs (dynamic random access memories) and high speed multi-metal EPROMs (erasable programmable read-only memories).
The foregoing description of the preferred embodiment of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. It is possible that the invention may be practiced in other MOS, bipolar, photoelectronic, microwave or photoacoustical fabrication technologies. Similarly, any process steps described might be inter-changeable with other steps in order to achieve the same result. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (22)

What is claimed is:
1. A process for avoiding stress-cracking in spin-on-glass used in high aspect ratio cavities between metal interconnects formed on an dielectric substrate supported on a semiconductor wafer, each said interconnect having sidewalls and a top surface, said process comprising:
(a) exposing said sidewalls and said top surface of each interconnect so as to permit subsequent selective tungsten deposition on said interconnects;
(b) growing a layer of selective tungsten on said exposed sidewalls and top of each interconnect;
(c) forming a spin-on-glass layer covering said interconnects, including filling cavities therebetween;
(d) soft-curing said spin-on-glass layer;
(e) etching said spin-on-glass layer to expose said top surfaces of said metal interconnects and leave free-standing portions of said spin-on-glass between said interconnects;
(f) removing at least that tungsten remaining on said sidewalls of said metal interconnects;
(g) hard-curing said spin-on-glass portions; and
(h) forming a layer of a dielectric material covering said spin-on-glass portions and said top surfaces of said metal interconnects.
2. The process of claim 1 wherein said layer of dielectric material is selected from the group consisting of spin-on-glass, polyimides, silicones, silicon oxides, silicon nitrides, silicon oxynitrides, and vapor-deposited oxides, said dielectric material being deposited under conditions compatible with said metal interconnects.
3. The process of claim 2 wherein said layer of dielectric material comprises a material selected from the group consisting of spin-on-glasses, which are subsequently hard-cured, and vapor-deposited oxides.
4. The process of claim 1 wherein said metal interconnect substantially comprises aluminum or an alloy thereof.
5. The process of claim 1 wherein said tungsten is grown to a thickness of about 500 to 3,000 Å.
6. The process of claim 5 wherein said tungsten is grown by a self-limiting selective deposition process to a thickness of about 500 to 900 Å.
7. The process of claim 1 wherein said tungsten is removed from at least said interconnect sidewalls in a wet etchant consisting essentially of H2 O2.
8. The process of claim 1 wherein said aspect ratio is at least about 1.
9. The process of claim 8 wherein said aspect ratio is greater than 1.
10. A process for avoiding stress-cracking in spin-on-glass used in high aspect ratio cavities between metal interconnects formed on a dielectric substrate supported on a semiconductor wafer, each said interconnect having sidewalls and a top surface, said process comprising:
(a) exposing said sidewalls and said top surface of each said interconnect so as to permit subsequent selective tungsten deposition on said interconnects;
(b) growing a layer of selective tungsten on said exposed sidewalls and top of each interconnect;
(c) forming a first spin-on-glass layer covering said interconnects, including filling cavities therebetween;
(d) soft-curing said first spin-on-glass layer;
(e) etching said first spin-on-glass layer to expose said top surfaces of said metal interconnects and leave free-standing portions of said spin-on-glass between said interconnects to form slit-like voids therebetween;
(f) removing at least that tungsten remaining on said sidewalls of said metal interconnects;
(g) hard-curing said first spin-on-glass portions;
(h) forming a second layer of spin-on-glass covering said first spin-on-glass portions and said top surfaces of said metal interconnects, substantially filling said slit-like voids; and
(i) curing said second layer of spin-on-glass.
11. The process of claim 10 wherein said metal interconnect comprises aluminum or an alloy thereof.
12. The process of claim 10 wherein said tungsten is grown to a thickness of about 500 to 3,000 Å.
13. The process of claim 12 wherein said tungsten is grown by a self-limiting selective deposition process to a thickness of about 500 to 900 Å.
14. The process of claim 10 wherein said tungsten is removed from at least said interconnect sidewalls in a wet etchant consisting essentially of H2 O2.
15. The process of claim 10 wherein said aspect ratio is at least about 1.
16. The process of claim 15 wherein said aspect ratio is greater than 1.
17. A process for avoiding stress-cracking in spin-on-glass used in high aspect ratio cavities between metal interconnects formed on a dielectric substrate supported on a semiconductor wafer, each said interconnect having sidewalls and a top surface, said process comprising:
(a) exposing said sidewalls and said top surface of each said interconnect so as to permit subsequent selective tungsten deposition on said interconnects;
(b) growing a layer of selective tungsten on said exposed sidewalls and top of each interconnect;
(c) forming a first spin-on-glass layer covering said interconnects, including filling cavities therebetween;
(d) soft-curing said first spin-on-glass layer;
(e) etching said first spin-on-glass layer to expose said top surfaces of said metal interconnects and leave free-standing portions of said spin-on-glass between said interconnects;
(f) removing at least that tungsten remaining on said sidewalls of said metal interconnects;
(g) hard-curing said first spin-on-glass portions; and
(h) forming a layer of vapor-deposited oxide covering said first spin-on-glass portions and said top surfaces of said metal interconnects, leaving voids between said interconnects and said spin-on-glass portions substantially unfilled, said voids having a dielectric constant of approximately equal to 1.
18. The process of claim 17 wherein said metal interconnect comprises aluminum or an alloy thereof.
19. The process of claim 17 wherein said tungsten is grown to a thickness of about 1,000 to 3,000 Å.
20. The process of claim 17 wherein said tungsten is removed from at least said interconnect sidewalls in a wet etchant consisting essentially of H2 O2.
21. The process of claim 17 wherein said aspect ratio is at least about 1.
22. The process of claim 21 wherein said aspect ratio is greater than 1.
US07/873,920 1989-07-25 1992-04-24 Process for avoiding spin-on-glass cracking in high aspect ratio cavities Expired - Fee Related US5192715A (en)

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US07/652,306 US5119164A (en) 1989-07-25 1991-02-05 Avoiding spin-on-glass cracking in high aspect ratio cavities
US07/873,920 US5192715A (en) 1989-07-25 1992-04-24 Process for avoiding spin-on-glass cracking in high aspect ratio cavities

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US5382547A (en) * 1992-07-31 1995-01-17 Sultan; Pervaiz Void free oxide fill for interconnect spaces
US5310700A (en) * 1993-03-26 1994-05-10 Integrated Device Technology, Inc. Conductor capacitance reduction in integrated circuits
US5716888A (en) * 1993-06-30 1998-02-10 United Microelectronics Corporation Stress released VLSI structure by void formation
US5972803A (en) * 1994-04-20 1999-10-26 Texas Instruments Incorporated High throughput optical curing process for semiconductor device manufacturing
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US5407860A (en) * 1994-05-27 1995-04-18 Texas Instruments Incorporated Method of forming air gap dielectric spaces between semiconductor leads
US5894160A (en) * 1994-05-31 1999-04-13 Stmicroelectronics, Inc. Method of forming a landing pad structure in an integrated circuit
US5945738A (en) * 1994-05-31 1999-08-31 Stmicroelectronics, Inc. Dual landing pad structure in an integrated circuit
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US5663599A (en) * 1994-07-25 1997-09-02 United Microelectronics Corporation Metal layout pattern for improved passivation layer coverage
US5635428A (en) * 1994-10-25 1997-06-03 Texas Instruments Incorporated Global planarization using a polyimide block
US5508233A (en) * 1994-10-25 1996-04-16 Texas Instruments Incorporated Global planarization process using patterned oxide
US5924006A (en) * 1994-11-28 1999-07-13 United Microelectronics Corp. Trench surrounded metal pattern
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US6025260A (en) * 1998-02-05 2000-02-15 Integrated Device Technology, Inc. Method for fabricating air gap with borderless contact
US6232647B1 (en) 1998-02-05 2001-05-15 Integrated Device Technology, Inc. Air gap with borderless contact
US6177286B1 (en) * 1998-09-24 2001-01-23 International Business Machines Corporation Reducing metal voids during BEOL metallization
US20040046258A1 (en) * 1999-01-04 2004-03-11 Cronin John Edward Specially shaped contact via and integrated circuit therewith
US6734564B1 (en) 1999-01-04 2004-05-11 International Business Machines Corporation Specially shaped contact via and integrated circuit therewith
US6924555B2 (en) 1999-01-04 2005-08-02 International Business Machines Corporation Specially shaped contact via and integrated circuit therewith
US6022802A (en) * 1999-03-18 2000-02-08 Taiwan Semiconductor Manufacturing Company Low dielectric constant intermetal dielectric (IMD) by formation of air gap between metal lines
US6251799B1 (en) 1999-07-16 2001-06-26 Taiwan Semiconductor Manufacturing Company Method to provide low dielectric constant voids between adjacent conducting lines in a semiconductor device
US6734110B1 (en) * 1999-10-14 2004-05-11 Taiwan Semiconductor Manufacturing Company Damascene method employing composite etch stop layer
US20030051225A1 (en) * 2001-09-07 2003-03-13 Katsumi Mori Method for generating mask data, masks, recording media, and method for manufacturing semiconductor devices
US7007265B2 (en) * 2001-09-07 2006-02-28 Seiko Epson Corporation Method for generating mask data, masks, recording media, and method for manufacturing semiconductor devices
US20050270826A1 (en) * 2002-11-26 2005-12-08 Thomas Mikolajick Semiconductor memory device and method for producing a semiconductor memory device
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